Math is hard. Let's go shopping
On Sunday morning one of my contacts sent me a LinkedIn Post, meant to astonish and inspire me regarding the rapid temporal dynamics of Covid-19. His message was well-intended, but I wasn't as excited about the post as he was.
I opened up the post and was intrigued. The headline read: "See covid outnumbering malaria and malnutrition as a killer #1 this year."
The chart was a dynamic running chart. When you clicked on the chart you could see various causes of death listed, and covid 19 rapidly climbing from the very bottom of the chart to the very top, outnumbering all other causes of death in 2020!
Wow I thought. Could Covid 19 really be THE Top Killer in 2020? The chart showed it loud and clear. You could literally see covid-19-deaths increase by the day until covid-19 reached the very top in the speed of light. I became scared just by looking at it.
The people commenting under the post were terrified as well. I don't recall the exact wording but one person wrote something along the lines of "Oh my God. And here we are continuing business as usual when our lives are literally on the line." The person who created the chart proudly boasted about the scientific and educational value of her chart.
I sent this chart to various people in my network as a Sunday Morning Quiz. "Find the mistake". Forget about the NYT Crossword Puzzle. This was an even bigger challenge.
People who responded said:
"Wait a minute. Are the numbers for malaria correct?"
Yes, the numbers for malaria were correct. Given that the person who posted the chart works for the Melinda and Bill Gates Foundation, this is the least that you could expect.
'Shouldn't there be more people dying due to drugs?".
'Is Covid-19 really always the cause of death? I thought causal relationships could be only established in 12 percent in Italy? So people seem to be dying "with" covid-19, rather than "of" covid-19."
People had lots of critical points. Many of them were valid, and others were not. But they all missed the one critical and decisive point.
By now you might ask yourself: What was the problem with this chart?
The creator had deliberately left out 93 percent of causes of death. The chart showed a selection of 7 percent of deaths in the world. 7 percent. Take a moment to digest this number. So what was missing?
Every year 57 million people die in the world of various causes. The "top killers" are cardiovascular diseases (Roughly 18 million people according to the WHO) and cancers (10 million people according to the WHO). But neither cardiovascular diseases nor cancer were represented in the chart of "top killers". Instead, you could see covid-19 competing with Parkinson and Malaria, Hepatitis and terrorism.
The running chart ended with Covid-19 deaths in the 300.000 death range as the "top #1 killer". Just for accuracy: By today, we are at 468.000 people who died in the context of Covid-19 worldwide according to The World in Data.
It's easy to be the "top #1 killer" if you leave out the real killers.
It's easy to lie with statistics. I see posts and newspaper articles like this every single day. As a neuropsychologist, I was very lucky to have received excellent trained in statistics. But research shows that most people are not able to properly assess risks and probabilities. As a result, the public can be fooled. Effortlessly. With just a few simple tricks.
Now you might put your hope into experts. But even experts such as medial doctors are in most cases unable to properly deal with statistics and risk as Gerd Gigerenzer has shown in numerous studies.
The current crisis shows: We need critical thinking more than ever.
The good news: Everybody can learn statistics and critical thinking with just a few hours of proper training.
How can you develop your critical thinking? Here are a few easy hacks which I learned from Prof. Gerd Gigerenzer from the Harding Center for Risk Literacy.
1. Always look at absolute numbers.
2. Never look at risk in isolation. Always compare risks to other risks.
3. Make sure that your selection of risks is representative of the world around you.